Grill frame structure



FIG. 1 is a perspective view of a grill frame structure embodying the invention;

FIG. 2 is a second perspective view thereof;

FIG. 3 is a top view thereof;

FIG. 4 is a front view thereof;

FIG. 5 is left side view thereof;

FIG. 6 is a rear view thereof;

FIG. 7 is a right side view thereof; and,

FIG. 8 is a bottom view thereof.

The details shown in broken lines form no part of the claimed design. 

The ornamental design for a grill frame structure, as shown and described. 